Non-aqueous electrolyte secondary batteries such as a lithium secondary battery are widely used as a battery used for personal computers, cellular telephones, handheld information terminals and the like.
Non-aqueous electrolyte secondary batteries show abnormal heat generation in some cases due to internal short-circuit or external short-circuit. For securing safety in abnormal heat generation, a separator having a shut-down function is used. As the separator having a shut-down function, a polyolefin porous film is used.
Patent document 1 describes a laminated porous film obtained by laminating a heat-resistant layer containing cellulose ether and fine particles onto a polyolefin porous film. Patent document 2 describes a laminated porous film obtained by laminating an adhesion layer containing polyvinylidene fluoride onto a polyolefin porous film.